Lecture 16: Intro to Pathology of Musculoskeletal System and Metabolic Disorders

Question 1

Introduction

Answer 1

-↑’ing individual participation in high-speed travel and competitive and recreational sports; also is marked by significant ↑ in primary musculoskeletal system injuries
-gap between science and clinical applications of therapeutic exercise has been narrowed
-ability to document the influence and effects of exercise at the molecular and cellular levels has resulted in early functional rehabilitation,
prevention exercise programs, and the use of exercise as first-line intervention for many conditions
-more than 50% of injuries in the United States are to the musculoskeletal system and 28.6 million Americans incur musculoskeletal injuries each year: fractures, sprains, and dislocations account for nearly 50% of all
musculoskeletal injuries
-Arthritis is the leading chronic condition reported by Americans age 65 years and older
-3 weeks of bed-rest has a more profound impact on physical work capacity than 3 decades of aging

Question 2

Advances in Musculoskeletal Biotecnhology

Answer 2

-orthopaedic surgery has been revolutionized in many areas
-40%-80% of adults in primary care report only physical symptoms, leaving a large portion of clients with significant psychological distress undiagnosed
-women double their rate of musculoskeletal injury during ovulation when levels of estrogen are the highest-training and conditioning differently during different times of the month may help protect women from injury
-men ↑ their muscle volume about twice as much in response to strength training compared with women; men also experience larger losses in response
to detraining than women

Question 3

Aging and Musculoskeletal System-Overview

Answer 3

• participation in a regular exercise program
• strength training helps to offset loss in muscle mass
• “Boomeritis”-baby boomers are all getting up there in age now, try to do things like they did years and years ago when body was much younger

Question 4

Aging and Musculoskeletal System-Sarcopenia

Answer 4

• age-related loss in muscle mass, strength, and endurance accompanied by changes in the metabolic quality of the muscle: reduction in muscle mass and/or function
• muscle mass is lost at a rate of 4%-6% per decade starting ~ age 40 in women and 60 in men
• men and women, muscle strength can be maintained through exercise into 8th decade
• women more vulnerable to loss of lean tissue more so than males

Question 5

Aging and Musculoskeletal System-Joint and Connective Tissue

Answer 5

-loss of flexibility also contributes to ↑’d risk of falls and other injuries
-connective tissue, including fascia, articular cartilage, ligaments, and tendons, become less extensible with resultant ↓’d active and PROM: possible cause is related to fibrinogen, produced in the liver and
converted to fibrin, constantly circulating throughout the body to serve as a clotting mechanism should an injury occur
-fibrinogen normally leaks out of the vasculature in small amounts into the intracellular space and then adheres to cellular structures, causing microfibrinous adhesions among the cells; activity and movement normally break down these adhesions along
with macrophagic activity to dissolve unused fibrinogen/fibrin
-in the aging process, less fibrinogen and fewer macrophages are available: these factors, along with less physical activity and movement, allow
these microadhesions to accumulate in muscle and fascia, resulting in an ↑’d sense of overall stiffness
-others have shown that aging collagen has ↑’d cross-links between molecules ↑’ing the mechanical stability of collagen, but also contributing to ↑’d tissue stiffness
-regardless of the physiologic mechanism, physical activity has an important influence in alleviating stiffness
-degeneration or damage of articular cartilage with loss of water content contribute to a significant ↑ in incidence of OA with aging
-by age 60, as much as 80% of the population shows evidence of such, although only about 15% present with symptoms
-tendons exhibit a lower metabolic activity associated with aging
-age-related ↓ occurs in tensile strength
-joint proprioception declines with age
-need compression and decompression to move synovial fluid to get nutrients into cartilage

Question 6

Aging and Musculoskeletal System-Bone

Answer 6

-bone is remodeling constantly throughout life-while osteoclasts resorb the existing bone, new bone is being formed by osteoblasts
-primary influences affecting bone remodeling: mechanical stresses, calcium and phosphate levels in the extracellular fluid, hormonal levels of parathyroid hormone, calcitonin, vitamin D, cortisol, growth
hormone, thyroid hormone, and sex hormones
-bone density reaches a peak during an adult’s twenties and remains stable for ~ 2 decades
-by age 65, bone loss has progressed to a point where the older adult is predisposed to fractures, especially when other co-morbidities exist

Question 7

Muscle

Answer 7

• muscle function can be described in terms of strength and endurance
• strength: related to the diameter of the muscle fiber, which has been consistently shown to ↑ with strength training
• endurance: ability to work over time; local muscle endurance is distinguished from general body endurance as the ability of an isolated muscle group to continue a prescribed task rather than the ability to continue an activity for an extended period of time

Question 8

Strength Training

Answer 8

• produces substantial ↑’s in the strength, mass, power, and quality of skeletal muscle
• can ↑ endurance performance
• normalizes BP in those with high normal values
• reduces insulin resistance
• ↓’s both total and intraabdominal fat
• ↑’s resting metabolic rate in older men
• prevents loss of bone mineral density with age
• reduces risk factors for falls
• may reduce pain and improve function in those with OA in the knee
• strength gains: occur from enhanced neuromuscular activation over the initial 8 weeks and from ↑’d fiber density and hypertrophy during subsequent weeks
• significantly ↑’s muscle size and ↑’s energy requirements and insulin action in adults over age 65
• once or twice weekly achieves muscle strength gains similar to 3 days per week training in older adults and is associated with improved neuromuscular performance
• does not ↑ maximal oxygen uptake beyond normal

Question 9

Endurance Training

Answer 9

-can reverse the decline in physical conditioning associated with aging
-modest intensity can reverse 100% of the loss of cardiovascular capacity, returning healthy older adults to levels of aerobic power present in young
adulthood
-less than 2 days per week at less than 40% to 50% VO2 and for less than 10 minutes is generally not a sufficient stimulus for developing and maintaining
cardiovascular fitness in healthy adults

Question 10

Bone

Answer 10

-complete immobilization and weightlessness result in rapid onset of accelerated bone resorption: bone mass recovers when activity resumes, but whether bone loss is completely reversible is unknown

Question 11

Musculoskeletal System Disease-Cancer

Answer 11

• primary malignant bone and soft tissue tumors are rare
• metastatic disease of the musculoskeletal system is common
• lung, breast, and prostate are the 3 primary sites responsible for most metastatic bone disease
• cells typically invade the thin-walled lymphatic channels, capillaries, and venules as opposed to the thicker walled arterioles and arteries
• blood supply to the axial skeleton is extensive compared with that to the distal components of the extremities, and the spinal blood flow through the thin-walled, valveless veins is slow and sluggish
• bony thorax, lumbar spine, and pelvis are the most common components of the axial skeleton for seeding of cancer to occur
• therapists working with clients diagnosed with cancer must be vigilant for S & S suggestive of systemic compromise and be aware of common sites of metastasis for the particular primary tumor

Question 12

Musculoskeletal System Disease-Infection

Answer 12

• can originate in the musculoskeletal system or it can spread to the musculoskeletal system from elsewhere in the body
• staph and strep are the most common infecting agents
• patients with LBP, SI, or hip pain of unknown origin must be screened for medical disease

Question 13

Metabolic Disorders: Overview

Answer 13

-skeleton is a metabolically active organ that undergoes continuous remodeling throughout life with an annual turnover of cortical and trabecular
bone of about 10% of the adult skeleton

Question 14

Osteoporosis

Answer 14

• means porous bones
• combination of ↓’d bone mass and micro-damage to the bone structure that results in a susceptibility to fracture
• classifications: primary-most common; can occur in both genders at all ages; often follows menopause in women and later in life in men-two subtypes: postmenopausal/estrogen-deficient (type 1) and age related/senile (type 2)
• secondary: associated with medications, other conditions, or diseases
• cause of primary is unknown; secondary may be caused by prolonged drug therapy

Question 15

Osteopenia

Answer 15

• low bone mass

- can be precursor to osteoporosis

Question 16

Incidence of Osteoporosis

Answer 16

• more common in women, esp. postmenopausal who are estrogen deficient
• when affected, men have a higher morbidity and mortality than that of women, because they are older at time of fractures and more likely to have co-morbid conditions, malnutrition, and hospitalizations

Question 17

Risk Factors

Answer 17

-hormonal Status: ↑’d risk of osteoporosis in postmenopausal women d/t ↓’d estrogen production
-heredity/genetics: strong connection to the receptor for parathyroid hormone; body build is related to bone fragility
-ethnicity: bone mass correlates positively with skin pigmentation; black men have lowest risk of developing osteoporosis
-physical inactivity: combined with immobilization have been associated with ↓’d bone formation
-tobacco: cigarette smoking is associated with a reduction of bone mass and is well known risk factor for spinal and hip fractures
-alcohol: excessive intake alters osteoblast gene expression and matrix synthesis, thereby reducing the number of effective cells
-medications…
-long-term use of corticosteroids has been associated with the presence of osteoporosis
-most bone loss occurs during 1st 6 months of systemic corticosteroid therapy
-impair osteoblastic activity
-impair the maturation of preosteoblastic cells to osteoblasts
-↑ osteoclastic activity
-impair vitamin D-dependent intestinal calcium absorption causing secondary hyperparathyroidism
-depression: those with depressive disorders are more likely to have lower bone densities and higher levels of cortisol-regardless of activity levels
-diet and nutrition: high dietary ratio of animal to vegetable protein intake in older women leads
to femoral neck bone loss and greater risk of hip fracture, regardless of physical activity level in women 65 or older; female athlete triad: disordered eating, amenorrhea, osteoporosis

Question 18

Pathogenesis of Osteoporosis

Answer 18

• trabecular: center meshwork of bones, 20% of adult skeleton, 15% - 25% calcified (remainder is bone marrow, fat and blood vessels)
• cortical: outer substance of bone mass, 80% of skeletal mass, 80% - 90% is calcified
• bone turnover: surface event, so trabecular bone is more active d/t ↑’d surface area; more metabolically active and greater rate of turnover
• remodeling: constant process by which bone renews itself
• purpose: replacing fatigue-damaged older bone with new bone, source of minerals necessary for maintenance of mineral homeostasis
• osteoporosis develops when new bone formation falls behind resorption
• bone demineralization: deficit in hormonal levels, inadequate physical activity, or poor nutrition
• gender differences: men show an age-related compensatory ↑ in bone size that women do not, women have a higher tendency to demonstrate disconnection of the trabecular network after age 50

Question 19

Clinical Manifestations of Osteoporosis

Answer 19

• loss of height
• postural changes
• back pain
• fracture: Vertebral bodies, hip, ribs, radius, and femur are most common (in order)
• vertebral compression fractures are the most common…
• can occur without injury or fall
• pain is usually severe and tenderness localized to the site of fracture
• generalized bone pain is suggestive of metastatic carcinoma or osteomalacia

Question 20

Prevention of Osteoporosis

Answer 20

• no cure available, regular exercise, physical activity
• adequate calcium: fracture risk can be reduced by 50% if vitamin and nutrient requirements are met in the first 2-3 decades of life
• low-fat dairy and other calcium and magnesium rich foods and supplements are the primary means
• broccoli or kale, sardines or salmon with the bones, fresh or dried apricots, figs, turnip greens, oranges or calcium-enriched orange juice, tofu
• vitamin D helps the body absorb, synthesize, and transport calcium within the body, therefore necessitating adequate sunshine each day
• tx: adequate calcium intake (premenopausal: 1000 mg, postmenopausal: 1500 mg) and exercise; vitamin D (800 units/day)
• SERM (Raloxifene) – selected estrogen receptor modulator

Question 21

SIFTT for Osteoporosis

Answer 21

• no immediate benefit may be perceived so need long-term commitment
• educate about importance of each aspect of the intervention program
• calcium alone without exercise and adequate vitamin D cannot prevent osteoporosis regardless of how much calcium is taken
• adults don’t store up calcium so supplementation only provides necessary calcium for as long as the supplements are taken
• screening assessment: need to know S & S associated with osteoporosis to make referral; balance and fall assessment and falls prevention program is essential
• exercise and osteoporosis: reduces chronic pain syndrome and depression associated with osteoporosis; benefits of exercise are lost if exercise is discontinued in adults
• fracture prevention: identify hazards in the home or workplace, choose the appropriate gait-assistive device and teach to use it properly
• quality of life: needs to be considered along with general fitness and well-being; 80% of women 75 years old and older would rather be dead than have a hip fracture and live in long-term care

Question 22

Precautions and Considerations for Osteoporosis

Answer 22

-with known disease or high risk of disease, caution should be taken with certain evaluation and treatment techniques
-bone mineral density of spine is correlated with strength of spine extensors
-flexion exercises contraindicated for anyone with osteoporosis
-posterior pelvic tilt and partial sit-ups (minimal abdominal crunches, lifting the
head and upper torso only to the level of T6) do not appear to cause any anterior compressive force

Question 23

Osteomalacia

Answer 23

-softening of bone without loss of bone matrix
-insufficient mineralization of the bone matrix results from calcium, vitamin D, and/or phosphate deficiency (adult form of rickets)
-etiology: 2 primary causes-insufficient intestinal calcium absorption (very rare in the US d/t vitamin D supplementation; when it does occur you see it in the malnourished aging adult) or ↑’d renal phosphorus losses
-RF: conditions that adversely affect the absorption of calcium and the action of vitamin D; diseases of the small intestine, cholestatic disorders of the liver, biliary
obstruction, chronic pancreatic insufficiency
-patho: Intact bone matrix with ↓ in calcification of the matrix – osteoid (bone not matured or calcified)
-CM: diffuse, generalized aching and fatigue in the presence of anorexia and weight loss; proximal myopathy and sensory polyneuropathy; bone pain and periarticular tenderness; postural deformities: ↑’d thoracic kyphosis, heart-shaped pelvis, marked bowing of the femurs and tibia

Question 24

Pagets Disease

Answer 24

-second most common metabolic bone disease
-progressive disease of excessive bone resorption and formation-normal bone marrow is replaced by vascular and fibrous tissue
-excess bone formed lacks the structural stability of normal bone: leads to deformities, fractures, arthritis, and pain
-unknown cause
-patho: initial osteoclastic, resorptive stage: abnormal osteoclasts proliferate unrestrained, osteoblastic activity cannot keep up, fibrous tissue replaces bone: osteoblastic sclerotic phase: normal cancellous architecture is replaced by coarse, thickened struts of
trabecular bone and cortical bone is irregularly thickened, rough, and pitted
-CM: primarily affects the axial skeleton, lesions occur at multiple sites, pathologic fractures, bones change in shape, size and direction: bone pain, arthritis, deformities, and fractures; may cause changes in gait pattern (waddling gait) d/t coxa vara
-↑’d kyphosis and bowing of tibias and femurs
-neurologic: when involvement of the skull and spinal column occur, direct impingement; pagetic steal syndrome-hypervascular pagetic bone “steals” blood from the neural tissue; may include 8th cranial nerve involvement
-cardiovascular: d/t vasodilation of blood vessels in the bones and skin and subcutaneous tissues overlying the affected bones; when 1/3 to 1/2 of the skeleton is involved, the ↑’d CO can cause heart failure
-prognosis: varied course with good outcome if treatment begun early

Question 25

SIFTT for Paget’s Disease

Answer 25

• intervention similar to osteoporosis
• discussion of client injury during exam and tx
• recognition of possible fracture
• postoperative care
• exercise is recommeded